4-(N-benzyl-N-methylamino)pyridine acid salts and use in preparation of polymer-supported catalysts

ABSTRACT

A cross-linked polymer-supported 4-(N-benzyl-N-methylamino) pyridine material and process for its preparation in high yield and having effective physical and catalytic properties. The polymer supported catalyst is characterized by the suspension copolymerization of an organic phase containing the corresponding vinyl-substituted pyridine monomer, a styrene monomer, and a suitable cross-linking agent and free radical-generating catalyst in the presence of an aqueous phase containing a cellulose ether derivative as the stabilizing agent. A purified acid salt of the vinyl-substituted pyridine monomer useful in polymerizations and stable for storage as either a solid or an aqueous solution.

CROSS-REFERENCE

This application is a division of application Ser. No. 07/690,393, filedNov. 5, 1990 now pending, which is a continuation-in-part of U.S. patentapplication Ser. No. 247,152, filed Sep. 21, 1988, now U.S. Pat. No.5,015,706.

BACKGROUND OF THE INVENTION

This invention relates generally to polymer-supported catalysts havingpyridylamino functionality, and in particular to a cross-linkedcopolymer of vinyl-substituted 4-(N-benzyl-N-methylamino)pyridine and astyrene monomer derivative characterized by improved physical propertiesand marked catalytic activity, and further to an improved acid salt formof the 4-(N-benzyl-N-methylamino)pyridine monomer and the use of thesame for preparing polymer-supported catalysts.

By way of general background, it has been recognized for some time that4-dimethylaminopyridine (commonly referred to as "DMAP") and certain ofits dialkylamino analogs are highly effective catalysts for acylations,alkylations and other related reactions. Hofle, G., Steglich, W.,Vorbruggen, H., Angew. Chem. Int. Ed. Engl., 17, 569 (1978); Scriven, E.F. V., Chem. Soc. Rev., 129 (1983). Also recognized for some time hasbeen the desirability of a polymer-bound or supported version of suchDMAP-like catalysts in view of the potential advantages of ease ofrecovery and repeated use along with the adaptability of such catalystsin both static and flow systems. Although such polymers could besoluble, it is understood that insoluble, heterogeneous gel ormacroreticular resin beads provide the greater advantages in ease ofremoval and recyclability. Frechet, J. M. J., Deratani, A., Darling, G,Lecavalier, P., Li, N. H., Macromol. Chem. Macromol. Symp., 1, 91(1986); Patchornik, A., Chemtech, January, 1987, 58.

Accordingly, much investigation has taken place in search of aneffective polymer-supported DMAP-like catalyst. For example, Klotz andhis coworkers were the first to report such a polymer made by attachingan acid-functionalized dialkylaminopyridine to a polyethyleneiminepolymer. Hierl, M. A., Gamson, E. P., Klotz, I. M., J. Am. Chem. Soc.,101, 6020 (1979). Klotz in combination with others subsequently reportedsimilar functionalized polyimines, and demonstrated their catalyticability by kinetic experiments on the hydrolysis of ρ-nitrophenylcaproate. Delaney, E. J., Wood, L. E., Klotz., I. M., J. Am. Chem. Soc.,104, 799 (1982); Klotz, I. M., Massil, S. E., Wood, L. E., J. PolymerSc., Polymer Chem. Ed., 23, 575 (1985). These polymers suffered,however, from the drawback that the pyridine was attached to the polymerbackbone by an amide linkage which was susceptible to scission as whenregenerating the resin using sodium hydroxide in acetylation reactionsinvolving acyl halides.

Verducci and his coworkers reported attaching 4-piperidinylpyridine,among other DMAP-like moieties, to a Merrifield resin also through anamide bond. Guendouz, F., Jacquier, R., Verducci, J., Tetrahedon Lett.,25, 4521 (1984). The amide bond in this polymer, however, was reportedto stand up well on recycle in the catalytic acetylation of1-methylcyclohexanol at 70° C. and 24 hours.

Nevertheless, more popular approaches to achieve DMAP-like polymercatalysts have avoided the use of amide linkages altogether. Forexample, Shinkai and his coworkers reported attaching 4-chloropyridineto an aminomethylpolystyrene to yield a polymer-supported4-(N-benzyl-N-methylamino)pyridine (which functional group has commonlybecome known as "BMAP"). Shinkai, S., Tsuji, H., Hara, Y., Manabe, O.,Bull. Chem. Soc. Jpn., 54, 631 (1981). This polymer-bound BMAP materialwas reported to effectively catalyze simple esterifications, but theproduct achieved by Shinkai had the disadvantages of including a highpercentage of a secondary amine which interfered with the reactionunless alkylated prior to use.

Another group of investigators led by Tomoi has compared two otherapproaches to achieve a similar polymeric BMAP catalyst. Tomoi, M.,Akada, Y., Kakiuchi, H., Macromol. Chem., Rapid Commun., 3, 537 (1982).Tomoi reported, among other things, that a route involvingcopolymerization of the preformed BMAP monomer gave a better catalystproduct. However, more recently a group led by Frechet challenged thisconclusion, reporting that preformed chloromethylated polystyrene can bemodified readily and quantitatively to produce an even better catalyst.Frechet, J. M. J., Deratani, A., Darling, G, Lecavalier, P., Li, N. H.,Macromol. Chem. Macromol. Symp., 1, 91 (1986). Menger and his coworkershave also reported success in converting a linearchloromethylpolystyrene resin to the corresponding linear BMAP polymerwhich has proven effective in well-known DMAP-catalyzed processes suchas the conversion of linalool to linalyl acetate which has definitecommercial interest. Menger, F. M., McCann, D. J., J. Org. Chem. 50,3928 (1985).

The extent of work in this field has also led groups headed by Frechet,Tomoi, Manecke and Challa to study the effects of variation of thefrequency of BMAP-to-styrene units as well as variations ofcross-linking and of the length and nature of the spacer arm orcomponent separating the pyridylamino functional group from the polymerbackbone. To this end, numerous polymers have been reported by thesegroups with varying degrees of detail. Deratani, A., Darling, G. D.,Horak, D., Frechet, J. M. J., Macromolecules, 20, 767 (1987); Deratani,A., Darling, G. D., Frechet, J. M. J., Polymer 28, 825-830 (1987); 10thIntl. Conf. Heterocycl. Chem. (1985); Tomoi, M., Goto, M., Kakiuchi, H.J., Polym. Sc., Polym. Chem., 25, 77 (1987); Storck, W., Manecke, G., J.Mol. Cat., 30, 145 (1985); and Koning, C. E., Eshuis, J. J. W., Viersen,F. J., Challa, G., Reactive Polym., 4, 293 (1986).

In reviewing these collective efforts, as highlighted above, it isevident that the paramount interest to date has been to confirm theability to synthesize polymer-supported catalysts of these typesapproaching DMAP activity. Accordingly, little or no effort has goneinto characterizing in a quantitative or qualitative way the physical orchemical properties of the polymer compounds thus far obtained.Nevertheless, these same properties dictate the ultimate commercialutility of such polymeric catalysts in whatever reactions they are used.

For example, while these considerable scientific publications havedemonstrated the general or potential utility of polymeric catalysts ofthis type, nearly all have done so with polymers having low degrees ofcross-linking up to only about 2% by weight of the total polymerizablemonomer present. These prior art polymers have been reported and provento be mechanically weak and to exhibit noticeable breakage anddisintegration both as formed and during use, particularly with evenmoderate attempts at recycling. In addition, these polymers haveexhibited substantial swelling in excess of 100-200% by volume uponexposure to a solvent which has aggravated breakage upon recapture. Thisis a definite disadvantage in many commercial processes, for example,where space constraints are important.

Moreover, these polymers prepared according to the literature referencescontain significant amounts of granular powders; flake or otherirregular shapes instead of the predominant bead form that is preferred.Such unwanted particles are mechanically unstable and suitable for useonly in stirred-slurry or other reactors where clogging of filters orlines is not a concern and where recycling of the catalyst is notcontemplated. The gel-type bead segments that are present in thesereference materials are nonuniform in size or configuration, exhibitgreat deviation from the average or median size present, and do not showthe durable, hard form that is preferred. While Frechet has reportedmaking a 34% divinylbenzene (DVB) cross-linked macroreticular resin alsowithin this class, he reported and subsequent testing has confirmed thatit has inferior chemical and physical properties as a catalyst in theacylation of 1-methylcyclohexanol. In addition, Frechet's resin madefrom his preferred chloromethylated polystyrene process may containquaternary salt from unwanted side reactions which can react toring-open under strongly basic conditions as often encountered.

Therefore, while certain publications have reported the synthesis ofpolymer-supported DMAP-like resins and their general catalytic ability,there has been and remains today the need for a catalyst of this type inboth gel and macroreticular form that exhibits overall mechanicalstability as expected with higher degrees of cross-linking whileretaining effective chemical properties believed lost in such materials.Improved physical properties of surface texture and configuration,uniformity and durability are also desired, as are chemical propertiesapproaching the catalytic potency and universal acceptance of DMAP andits analogs.

Further, difficulties in handling the BMAP monomer starting materialhave been encountered. In particular, BMAP monomer in its free base formis quite reactive. As a monomer related to styrene, BMAP monomer tendsto polymerize readily and does not survive manipulations well. Forexample, even distillation in a falling film still under high vacuumproduces very low recovery of BMAP monomer free base. Purification bycrystallization is also difficult as BMAP monomer free base is a lowmelting solid. Consequently, present preparations of polymer-supported4-(N-benzyl-N-methylamino)pyridine catalysts employ relatively impureBMAP monomer.

In synthesizing the free base, the BMAP monomer according to thereferences above is generally isolated as a solution of a crude productwhich may contain a number of useless, even interfering, by-products.Among these may be mineral oil, unreacted vinylbenzyl chloride and4-methylaminopyridine (MAP). Additional unknown compounds andintractable materials are also present. The presence of theseby-products in the BMAP monomer starting material, and the previousinability to effectively purify it, have detracted from the purity ofthe catalyst product and resultantly from its efficient and effectiveuse.

Also, the polymerizations themselves have been required to be carriedout relatively quickly after synthesis of the BMAP monomer due to itsreactivity and inherent instability. As a result, preparation of themonomer has been limited to the quantity needed for immediate use as thefree base cannot be stored for any appreciable length of time pendingfurther use. Preparation of quantities of monomer exceeding amountsimmediately consumable have typically resulted in loss of this excessand waste of the materials.

SUMMARY OF THE INVENTION

The applicants' present invention addresses these needs in the discoveryof a cross-linked polymer-supported 4(N-benzyl-N-methylamino)pyridinematerial of superior physical properties and high activity andeffectiveness as a catalyst for acylation, alkylation and other relatedreactions. This polymeric BMAP catalyst is prepared through the freeradical suspension copolymerization of an organic phase comprising thevinyl-substituted BMAP monomer free base, a styrene monomer and asuitable free radical-generating catalyst and cross-linking agent in thepresence of a selected aqueous suspending medium. Further, an acid saltform of the BMAP monomer has been discovered which is stable as a solidor in solution and is easily neutralized to the free base for use in thesuspension copolymerization process.

In its preferred form, the Applicants' polymer-supported BMAP materialis characterized by its generally spherical and smooth bead form andsubstantially uniform size ranging up to about 1.0 mm in diameter andexhibiting minimal deviation from the median or average bead size in agiven batch. The beads are hard and durable, being both easilyrecoverable following copolymerization and readily recyclable in use.The beads may have a gel or a macroreticular structure, as desired,depending upon the degree of cross-linking and other factors such as thepresence of a suitable diluent such as an organic solvent in thecopolymerization process. The beads are also characterized by theabsence of any significant amount of granular powders, flake or otherirregular particles either as originally formed or as the result ofunwanted deterioration from normal catalytic use. The beads have furthershown to have highly effective catalytic activity approaching that ofDMAP in the reactions tested.

Further, this preferred polymer-supported BMAP material is characterizedby its suspension copolymerization process and, in particular, by theuse of an aqueous phase comprising a cellulose ether derivative as thestabilizing or suspending agent. With this preferred suspensioncomponent, high percentages of the desired polymer beads have beenrecovered in excess of 90% by weight of the total product which exhibitthe surprisingly superior physical properties of shape, size, hardnessand overall quality and appearance described herein while alsodemonstrating unexpected and effective catalytic utility also described.

Still further, the BMAP monomer containing the amino functionality hasbeen discovered to form a stable salt with a relatively strong acid suchas hydrochloric acid, sulphuric acid, hydrobromic acid and the like.Surprisingly, these acid salts of the BMAP monomer are stable as solidamine salts. More surprisingly, these BMAP acid salts are alsorelatively stable in an aqueous solution of the parent acid. Moreover,these acid salts can be stored for extended periods pending later use,and particularly use in the Applicants' same suspension copolymerizationprocess where the salt is either neutralized in situ immediately priorto the polymerization reaction or is neutralized and then isolatedimmediately before use. Also, these BMAP acid salts used in this mannermay be stored either as the solid form or as an aqueous solution of theparent mineral acid.

One advantage of the present invention is accordingly the economicpreparation of the BMAP monomer in quantities which may be larger thanimmediately needed. Surplus BMAP monomer may be converted to one of theacid salts of the present invention and stored for future use.

A second advantage of the present invention is that the BMAP monomerfree base is purified by isolation as an acid salt according to theApplicants' discovery, which salt is then substantially free from theimpurities found in previous processes. This purified monomer may thenbe used in the suspension copolymerization process with the resultantpolymer being of significantly greater purity than those polymersprepared from unpurified BMAP monomer.

A further advantage is the convenience of use of the acids salts of thepresent invention. The salts are easily converted to the BMAP free baseby neutralization with a base.

A still further advantage is an improved process for preparingpolymer-supported 4-(N-benzyl-N-methylamino) pyridine catalysts usingthe BMAP acid salts of the present invention.

Related objects and advantages of the present invention will be apparentfrom the following description.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the several embodiments andspecific language will be used to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended, such further applications of theprinciples of the invention as illustrated therein being contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

In accordance with the above, the applicants have discovered acommercially significant DMAP-like polymer resin containing4-methylaminopyridine groups functionally bound to a cross-linkedstyrene backbone at the 4-amino site through a vinylbenzyl linkage. Thepreparative process of choice comprises the suspension copolymerizationof vinyl-substituted 4-(N-benzyl-N-methylamino)pyridine with a styrenemonomer and a suitable cross-linking agent and free radical-generatingcatalyst. This is contrasted by the indirect method reported in theliterature which involves subsequently attaching 4-pyridineamine groupsto a preformed chloromethylated polystyrene resin. The applicants foundthat this indirect method incorporated less pyridylamino functionalgroups onto the preformed polymer, required longer reaction times andresulted in greater likelihood of contamination from quaternary saltformation or residual chloromethyl components. In any case, thepreferred polymer resins of the invention have been identified byinfrared (I.R.) and elemental combustion analysis and their catalyticactivity has been confirmed by reactions such as those reported inExample 4 below involving a Fries ester rearrangement and theacetylation of 1-methylcyclohexanol. In each reaction, the applicants'heterogeneous polymeric catalyst performed effectively and comparedfavorably with DMAP used under homogeneous conditions.

Referring further to the process embodiment of the invention, the terms"free radical suspension copolymerization" are well known to thoseskilled in this art and comprise the process of polymerizing a comonomermixture which has been suspended in the form of droplets in a medium ofsome composition in which the monomers are at least substantiallyinsoluble. The discrete nature of these droplets and the size andstability of the suspension depend in large part on the nature of themedium used including its individual components or additives, as well ason various physical factors in the procedure such as stirring rate,temperature and the like. The medium used in this invention is anaqueous phase suspension of a particular class of stabilizing agent asdescribed below.

As the copolymerization proceeds, these droplets appear and take onvarious forms which will affect their physical and chemical propertiesin later use. Although it is common to refer to all such polymerdroplets as "beads," in fact they may range from granular powders,flakes or other irregular-shaped particles such as produced by the priorart processes discussed above to the predominantly uniform and smooth,hard spherical beads achieved by the applicant's invention.

One method of promoting the copolymerization is to provide a suitablecatalyst which when elevated to a sufficient temperature will decomposeto provide free radicals which function as initiators for the reaction.Two general classes of such free radical-generating catalysts are known,those being peroxides and azo compounds. The selection of an initiatorwithin these groups, and its amount and method of use, is within theknowledge and skill of the art and depends on availability, on thespecific comonomer mixture used and on other factors affecting thereaction. The catalyst used in the applicants' work has been an azocompound identified as 2,2'-azobis-(2,4-dimethylvaleronitrile) andmarketed by E. I. du Pont de Nemours & Company (DuPont) under thetrademark Vazo 52. The preferred range of this catalyst has been fromabout 0.1-1.0% by weight of the total comonomer components used. It isnonetheless understood that other catalysts within these groups aresimilarly suited for this purpose and are within the scope of theinvention.

As the copolymer of the applicants' invention is an insoluble orheterogeneous material, a suitable cross-linking agent must also beincluded in the organic component during the copolymerization process.Many such cross-linking agents are commercially available, and theirutility and interchangeability in reactions such as the process at handare well known to those skilled in this art. The applicants have to dateused a commercial divinylbenzene (commonly referred to as "DVB") forthis purpose in amounts varying according to the desired physicalstructure of the reaction product as further discussed below. In anycase, however, it is understood that other suitable cross-linking agentsare known to exist and are within the scope of the invention.

The reaction conditions for the preferred process such as thetemperatures and times for the copolymerization to occur as well asappropriate equipment and procedures such as the desirability ofagitation and the like are also well known to those practiced in thisart. Accordingly, the same require little further elaboration in thisspecification. For example, it is known that the temperature to initiatepolymerization depends as a practical limit on the decompositiontemperature of the free radical-generating catalyst used. As somereactions in this class are exothermic, little or no additional heatingis necessary although some may be desirable at later stages to assurecomplete copolymerization of the monomer present. For the applicants'preferred Vazo 52 catalyst, an initiation temperature of about 55° C.was employed with an elevated temperature of about 85° C. used to finishoff the reaction. With other suitable catalysts, this initiationtemperature may increase or decrease significantly coupled withcompleting the reaction at temperatures up to or at reflux of about 100°C. or above. It is similarly known, for example, that oxygen inhibitsthese reactions and was therefore kept from the system in the Examplesbelow by maintaining a nitrogen purge during the copolymerizationprocess.

Referring now to a second embodiment, the cross-linked polymer-supportedBMAP material in accordance with the invention is characterized by beingsuspension copolymerized in the presence of a particular aqueous phasewhich comprises a cellulose ether derivative as the stabilizing orsuspending agent. Suitable cellulose ether derivatives (and examples oftheir available commercial trademarks and sources) includemethylcellulose (such as Methocel A from Dow Chemical Corporation ofMidland, Mich. and Culminal from Aqualon Company of Wilmington, Del.);hydroxyethylcellulose (such as Natrosol 250 from Aqualon and Cellosizefrom Union Carbide Corporation of Danbury, Conn.);hydroxypropylcellulose (such as Klucel J from Aqualon); hydroxypropylmethylcellulose (such as Methocel E, F, J and K and 50-123 from DowChemical and Culminal MHPC from Aqualon); hydroxyethyl methylcellulose(such as Culminal from Aqualon); carboxymethyl methylcellulose (such asCMMC from Aqualon); hydrophobically-modified hydroxyethylcellulose (suchas HMHEC WSP-M 1017 from Aqualon); carboxymethyl hydroxyethylcellulose(such as CMHEC 37L from Aqualon); and hydroxypropylhydroxyethylcellulose (such as Natrovis from Aqualon). In many cases,these trademarks represent classes or series of compounds offered bythese companies which will work effectively in the present process.Moreover, this listing of cellulose ether derivatives is not exhaustiveas there are other such derivatives both naturally-occurring andsynthetic which are also suited for this purpose and are within thescope of the invention.

The amount required of this stabilizing additive in the aqueous phase toeffect the desired copolymerization of the present invention will varyaccording to the cellulose ether used as well as other factors. Fromwork thus far some preference has been shown for hydroxypropylmethylcellulose (such as Methocel 50-123 from Dow Chemical),hydrophobically-modified hydroxyethylcellulose (such as HMHEC WSP-M 1017from Aqualon) and carboxymethyl hydroxyethylcellulose (such as CMHEC 37Lfrom Aqualon) in preferred concentrations up to about one-half percent(0.50%) by weight of the total aqueous phase. Most preferred have beenconcentrations of about one-tenth percent (0.10%) by weight. Thelimiting factors in selecting these derivatives and amounts arepractical ones such as availability and ease of use and process concernsaffecting viscosity and the proper maintenance of the suspension onceachieved. In any case, the use of these cellulose ether derivatives inthe aqueous phase of the present invention has yielded superiorcopolymer beads having effective physical properties as well as highlyactive catalytic functionality. These results were unexpected and are asignificant improvement over the additives reported in the literaturefor preparing similar polymer-supported DMAP-like catalysts.

The selection of materials for the organic monomer phase in accordancewith the invention involves preparing crude vinyl-substituted4-(N-benzyl-N-methylamino)pyridine (BMAP) monomer. This preparation maybe accomplished, for example, through the reaction of4-(N-methylamino)pyridine with vinylbenzylchloride as reported in the1982 Tomoi article previously referenced, although other methods may beavailable which would likely result in the characteristic vinyl-linkageinstability and impurity in the monomer product. Further, the crude BMAPmay be prepared well in advance, purified by transformation from thefree base to the acid salt form, and stored for later use whereupon itis neutralized, all according to the Applicants' further discovery asdescribed in more detail as the fourth embodiment found below. Alsopresent in the organic phase is a styrene monomer component includingstyrene itself and/or a substituted styrene derivative such asethylstyrene, which is similarly suited for this purpose and is withinthe scope of the invention. Still further, there is a suitable freeradical-generating catalyst and cross-linking agent in accordance withthe descriptions above.

The concentration and ratio of these monomer materials in the organicphase will vary appreciably depending upon the desired physical andchemical characteristics of the resulting copolymer product. BMAPloading is a convenient measure as the amount of pyridylamino groupspresent has a direct relationship to the functioning of the copolymerresin as a catalyst in acylation, alkylation or other related reactions.For example, the preferred polymer-supported material has beensuccessfully prepared in accordance with the invention across a widerange of BMAP loading up to about 50% by weight of the BMAP monomercompared to the total monomer present in the organic phase. This isapproximately equivalent to a mole percent up to about 33% and to molarratio up to about 1:2 of BMAP monomer to total styrenic monomer in theorganic phase. In this regard, the term "total styrenic monomer" ismeant to include styrene and any styrene derivatives such asethylstyrene and divinylbenzene, and is in deference to the fact thatcommercial DVB cross-linking agent is a styrene derivative having someunreacted ethylstyrene component. For example, the 55% DVB used in theExamples below typically has about 45% ethylstyrene remaining in thematerial. This entire DVB component including the extraneous styrenicmaterial is included in the BMAP loading calculation. In a similarmanner, the most preferred BMAP loading from work performed to date isabout 34% by weight of BMAP monomer compared to total styrenic monomerin the organic phase, which equates to about 20 mole percent and to amolar ratio of about 1:4.

As alluded to earlier, the amount of agent such as divinylbenzene in theorganic monomer phase directly affects the degree of cross-linking andto a large extent both the physical and chemical properties of theresulting copolymer catalyst product. With this in mind, decreasingconcentrations of DVB below about 8-10% by weight in accordance with theinvention has produced effective gel resins that are generallytranslucent and hard, durable beads in appearance and exhibit increasingswellability and accompanying activity typical of lower degrees ofcross-linking. Increasing concentrations of DVB above about 8-10% byweight, on the other hand, has produced similarly effective gel resinsthat are generally harder bead forms less subject to swelling ordisintegration during use and exhibit some possible loss of accompanyingactivity typical of such higher degrees of cross-linking. By increasingstill further the concentration of DVB coupled with the inclusion of asuitable diluent such as an organic solvent in the monomer phase duringcopolymerization, the resulting product has been effectively changedfrom a gel to a macroreticular bead form as determined by the presenceof a permanent pore structure and opaque appearance typical of suchresins upon later removal of the solvent. Although many suitablesolvents exist for this purpose, the applicants have employed a VMPNaphtha material distributed by Chem Central of Indianapolis, Ind. inabout 33% by weight of the total organic phase. As shown in Example 4below, the applicants' preferred polymeric material has shown effectivecatalytic properties at 15% cross-linking in both gel and macroreticularforms. Selection of the appropriate cross-linking and resin form for agiven catalytic reaction, including the nature and amount of any solventused, is well within the knowledge and skill of those practiced in thisart and is within the scope of the present invention.

Referring to still a third embodiment, the cross-linkedpolymer-supported BMAP material of the invention is furthercharacterized and distinguished from the art by the same physical andcatalytic properties which have been surprisingly discovered. Inparticular, the preferred copolymer material has been prepared in highyield well in excess of 90% of the total recovered product. Moreimportantly, the preferred material has shown little or no evidence ofclumping or of the presence of granular powders, flake or otherirregular material to hamper later use or recycling of the catalyst. Onthe contrary, the preferred material has exhibited a generally smoothand spherical bead form with the further advantage of a substantiallyuniform size distribution ranging up to about 1.0 mm in diameter and aminimal deviation from the median or average bead size in a givenreaction. Subsequent testing has shown these same preferred copolymerbeads resist attrition as a result of swelling in the case of gel resinsand overall are hard, highly durable and easily recyclable in both geland macroreticular forms. These beads have further shown surprisinglyeffective catalytic activities approaching those of DMAP in reactionstested as highlighted in Example 4 below, but with the added advantagesattendant their heterogeneous structure.

As noted above, a fourth embodiment of the present invention involvesisolating and purifying the BMAP monomer as an acid salt from the crudevinyl-substituted 4-(N-benzyl-N-methylamino)pyridine monomer reactionsolution. As used in this context, the term "acid salt" is meant toinclude both BMAP acid salt in solution and BMAP acid salt in solidform. After the reaction is complete, the reaction solution contains anumber of by-products and unreacted reactants, most of which areincapable of forming a salt. Past attempts in the references to purifythe monomer have led to very low recovery of the compound. For example,purification by crystallization is very difficult as the monomer isrelatively low melting and usually handled as a liquid. Attempts topurify the monomer by distillation have also met with limited success.Even when a falling film still has been used under high vacuum themonomer yields are quite low.

In contrast to these failed attempts, the Applicants have discoveredthat the crude BMAP monomer may be readily isolated and purified with anacid sufficiently strong to form an acid salt with the monomer.Surprisingly, these acid salts of the BMAP monomer free base are stableto repeated and normal handling and further are stable to extendedstorage pending later use. Moreover, subsequent polymerizations usingthis this BMAP monomer, once neutralized, result in as good or betterperformance of the polymer products along with attendant benefits suchas increased purity, reactivity, efficiencies of operation and the like.

One manner of isolating the BMAP monomer as an acid salt is bysubjecting the crude BMAP monomer, perhaps dissolved in a solventsubstantially insoluble in water such as toluene, to extraction with anaqueous acid such as hydrochloric acid, sulphuric acid, hydrobromic acidor p-toluenesulfonic acid, methanesulfonic acid, formic acid, phosphoricacid or the like, but preferably hydrochloric acid. The extraction maytake place while the BMAP monomer is still present in the reactionsolvent from its preparation. Addition of the acid in this way resultsin the formation of two layers, one an organic layer and the other anaqueous layer. The neutral compounds, i.e., impurities, present insolution and incapable of forming a salt remain in the organic layer,while BMAP monomer and minor compounds capable of forming a salt aretaken into the aqueous layer. For example, these minor compounds mayinclude methylamino pyridine and comparable side products. The organiclayer is then separated from the aqueous layer by decanting or by othermethods known to those ordinarily skilled in the art. The resultingseparated aqueous solutions containing the BMAP acid salt having apurity greater than 90% may then be stored for later use if so desired,or may be used presently in whole or in part. By way of illustration,the acid salt solution may be used in the Applicants' suspensioncopolymerization process or in any polymerization process such as thosedescribed in the references above. Still further, other uses for theacid salt or the neutralized BMAP monomer of the present invention willbe readily apparent to those of ordinary skill in the art.

For use in the Applicants' copolymerization process, the aqueous BMAPacid salt must be converted back to the BMAP free base. Conversion tofree base can be accomplished by adding a suitable neutralizing aqueousbase such as ammonia or sodium hydroxide to the solution, preferablyammonia. Addition of this aqueous base results in a suspension fromwhich BMAP free base may be extracted with a substantially waterinsoluble solvent such as dichloromethane or styrene, preferablystyrene.

Most preferably, a styrene or a substituted styrene derivative such asethylstyrene is used as this extraction solvent and it is desirable thento add to the resultant BMAP/styrene solution the other ingredientscomprising the organic phase for the suspension copolymerization processdescribed above. The copolymerization then proceeds as also describedpreviously. Thus, use of a styrene derivative as the extractant isexceedingly practical as a manufacturing step since it eliminates anydrying or other secondary recovery step.

A second manner of isolating BMAP acid salt is by recovering it as asolid precipitate. The crude BMAP monomer, perhaps still dissolved inthe organic solvent from its preparation, is subjected to asubstantially anhydrous mineral acid such as gaseous hydrogen chloride,hydrogen bromide, p-toluenesulfonic acid, methanesulfonic acid orcombination of these acids dissolved in a convenient solvent, forexample acetic acid. When the crude BMAP monomer free base solution issubjected to this substantially anhydrous acid, solid and purified BMAPacid salt is formed which may be removed from solution by any of themeans well known in the art, such as filtration or centrifugation. ThisBMAP solid salt is substantially pure in the sense that it is free fromthe non-salt forming compounds present in the original reactionsolution. Typically the BMAP solid salt is greater than 90% pure. Thesalt may then be repeatedly handled and stored for extended periodspending later use in Applicants' copolymerization, or otherpolymerizations such as those of the above references, or other mannersapparent to those ordinarily skilled in the art. It may also be furtherpurified if desired using any conventional means for recrystallization,for example re-dissolution and precipitation using conventionalmaterials.

When it is later desired to use the BMAP solid salt in Applicants'suspension copolymerization, it must first be converted to BMAP freebase. Conversion may be done as described above by neutralization with asuitable aqueous base followed by extraction of the neutralized BMAPmonomer with a substantially water insoluble solvent, such asdichloromethane or styrene. As also described above, when styrene isused as the extraction solvent the other reactants necessary for thesuspension copolymerization may then be added directly to the separatedstyrene phase for subsequent reaction.

Examples 6-8 are representative of the preparation and isolation of theApplicants' preferred BMAP acid salts as solids. Examples 9-12 similarlydescribe the purification of this BMAP monomer by forming aqueoussolutions of its acid salts after its initial formation. Example 13describes what is presently considered the most preferred embodiment,involving formation of the hydrochloric acid salt of BMAP in water toextract and purify the BMAP monomer followed by storing this BMAPmonomer hydrochloride solution if desired, recovering the free basemonomer from the acid solution by treatment with strong base and,simultaneously, extracting the BMAP monomer into sytrene solution whichis then reacted to form the preferred polymer-supported4-(N-benzyl-N-methylamino)pyridine catalysts after addingdivinylbenzene, initiator, water, and a suspending agent.

Example 14 describes a study comparing the stability of unpurified BMAPmonomer free base and BMAP acid salts prepared according to the presentinvention. The acid salts were shown to be significantly more stable tostorage. After eight days storage at -5° C. the unpurified BMAP monomerformed a residue substantially comprising the spontaneous polymerizationproduct of the monomer, representing 12% of the original monomer. Incontrast, a hydrochloric acid salt solution of the BMAP monomer formedpolymeric residue representing only 5% of the original BMAP monomerafter eight days storage at 3° C. Solid BMAP hydrochloride stored atambient temperature for four weeks formed polymeric residue representingless than 1% of the original monomer. Decreased temperatures do notadversely affect the stability of the solid salt.

Reference will now be made to specific examples for the purpose offurther describing and understanding the features of Applicants'preferred embodiments as well as their advantages and improvements overthe art. In this regard, where possible, specific reference has beenmade in the Examples to known prior art processes in order to betterunderstand and distinguish Applicants' invention herein. It is furtherunderstood that these Examples are representative only, and that suchadditional embodiments and improvements of the same are within thecontemplation and scope of Applicants' invention as would occur tosomeone of ordinary skill in this art.

EXAMPLE 1 Suspension Copolymerization Procedure

The following is the procedure used by the applicants in preparing thepolymer-supported BMAP catalyst materials according to the previouslydescribed embodiments of the invention:

An aqueous phase was first prepared using water and one of the celluloseether derivatives listed in Example 2, as the stabilizing or suspendingagent. 150 ml of this aqueous phase was added to a 300 ml round-bottomflask fitted with a condenser, nitrogen purge ports, a thermometer and astirrer equipped with a glass stirring shaft and Teflon blade. Theaqueous solution was purged with nitrogen, stirred and brought to theappropriate reaction temperature to permit free radical generation bythe catalyst being used (with Vazo 52, this was about 55° C.).Approximately 30 g of one of the organic monomer phases also listed inExample 2 was then added to the stirred aqueous phase below the liquidsurface through a long-necked funnel. The resulting dispersion wasmaintained at the reaction temperature (about 55° C.) with continuedstirring and nitrogen purge for 3 hours until the copolymerization wassubstantially complete. The dispersion was then heated to about 85° C.and maintained at that temperature for 16 hours with continued stirringand nitrogen purge to finish off the reaction, followed by cooling toroom temperature. The insoluble cross-linked polymer-supported BMAPresin beads were removed from the remaining liquid by filtration, rinsedand dried, then their identification and composition confirmed throughinfrared (I.R.) and elemental combustion analysis.

EXAMPLE 2 Aqueous and Organic Phase Preparations

For use in the procedure of Example 1, aqueous phase solutions wereprepared in accordance with the invention using each of the celluloseether derivatives previously identified in the specification as thestabilizing or suspending agent. These included methylcellulose (such asMethocel A from Dow Chemical Corporation of Midland, Mich. and Culminalfrom Aqualon Company of Wilmington, Del.); hydroxyethylcellulose (suchas Natrosol 250 from Aqualon and Cellosize from Union CarbideCorporation of Danbury, Conn.); hydroxypropylcellulose (such as Klucel Jfrom Aqualon); hydroxypropyl methylcellulose (such as Methocel E, F, Jand K and 50-123 from Dow Chemical and Culminal MHPC from Aqualon);hydroxyethyl methylcellulose (such as Culminal from Aqualon);carboxymethyl methylcellulose (such as CMMC from Aqualon);hydrophobically-modified hydroxyethylcellulose (such as HMHEC WSP-M 1017from Aqualon); carboxymethyl hydroxyethylcellulose (such as CMHEC 37Lfrom Aqualon); and hydroxypropyl hydroxyethylcellulose (such as Natrovisfrom Aqualon). The aqueous solutions were prepared according to themanufacturer's directions, and generally involved dispersing appropriateamounts of the additive in water at about 85° C. followed by cooling toroom temperature to effect proper hydration.

Organic phases for use in the procedure of Example 1 were also preparedin accordance with the invention with varying concentrations ofvinyl-substituted BMAP monomer, with styrene itself as the styrenicmonomer of choice, and with 55% DVB and Vazo 52 as the cross-linkingagent and copolymerization catalyst. BMAP loading was varied at about15%, about 20%, about 34% and about 50% by weight of the BMAP monomercompared to the total monomer component in the organic phase. This isapproximately equivalent to a range of about 7.8 mol %, about 11 mol %,about 20 mol %, and about 33 mol % and to a range of molar ratio ofabout 1:11, about 1:8, about 1:4 and about 1:2 of BMAP monomer to totalmonomer present. For example, approximately 30 g of organic phase at 2%cross-linking and 34% BMAP loading contained 11.2 g BMAP monomer, 1.18 g55% DVB, 19.88 g styrene and 0.16 g Vazo 52. A similarly 4% cross-linkedmaterial at 15% BMAP loading contained 3.73 g BMAP monomer, 1.82 g DVB,18.93 g styrene and 0.12 g Vazo 52, at 20% BMAP loading contained 8.26 gBMAP monomer, 2.74 g DVB, 29.14 g styrene and 0.16 g Vazo 52, and at 50%BMAP loading contained 15.00 g BMAP monomer, 2.20 g DVB, 13.91 g styreneand 0.16 g Vazo 52. By way of further example, 30 g of organic phase at4% cross-linking and 34% BMAP loading contained 11.2 g BMAP monomer,2.37 g 55% DVB, 18.94 g styrene and 0.16 g Vazo 52. Still furtherorganic phases were prepared at these four levels of BMAP loading withvarying amounts of DVB to prepare copolymer products at levels ofcross-linking increasing by 2% up to 12% by weight of the organic phase.These additional mixtures were prepared according to known procedures,but simply with stoichiometrically varying amounts of individualcomponents to arrive at the concentrations desired.

EXAMPLE 3 Polymer-Supported BMAP Catalyst

Employing the suspension copolymerization procedure of Example 1 and theaqueous and organic phases of Example 2, the applicants prepared,isolated and identified by I.R. and elemental combustion analysis thepolymer-supported BMAP materials obtained from these reactions inaccordance with the present invention. In each case, the copolymer yieldwas well in excess of 90% by weight of the total reactants and wascharacterized by a predominant and generally smooth and spherical beadform and substantially uniform size ranging from up to about 1.0 mm indiameter with a minimal deviation in bead size in each yield. Eachcopolymer product was further characterized by the absence of clumpingor any significant extraneous material such as the granular powders,flake and other irregular-shaped particles common to literaturepreparations. Still further, the bead form of each product was hard,durable and generally translucent giving the overall appearance of aneffective gel resin for catalytic purposes. Microscopic examination ofthe copolymers showed no fractures or bubbles in the particle beads asformed. In subsequent testing repeated swellings in a toluene solventand by stirring in a toluene slurry for more than 2 days, no significantfracturing of the recovered beads was found thereby confirming theirdurability and recyclability in a commercial setting.

Although preferences as to cross-linking, BMAP loading, the selection ofthe preferred stabilizing additive and the like will vary in practicedepending on many factors, not the least of which is the particularcatalytic reaction of interest, certain preferences have been identifiedat least under the procedures and reactions investigated to date. Inthis regard, the stabilizing additives most preferred have been Methocel50-123, HMHEC and CMHEC 37L as previously described. Thepolymer-supported BMAP resins most preferred have similarly possessed a34% BMAP loading with either 2% or 4% cross-linking.

EXAMPLE 4 Comparison of 15% Cross-Linked Gel & Macroreticular Resins

Initially, an aqueous phase was prepared by heating 50 ml of water toabout 85° C. in an appropriate vessel. With brisk stirring, 0.30 g ofMethocel 50-123 was added and the mixture was stirred for about 5minutes. 150 ml of cold water was added and the mixture was then cooledto room temperature with periodic stirring for about another hour tocomplete solvation of the stabilizing agent.

Two organic monomer mixtures were prepared using the following recipes:For the gel resin, 10.20 g BMAP monomer (as used in Example 2), 11.62 gstyrene, 8.18 g 55% DVB and 0.15 g Vazo 52 were combined with stirringto give a homogeneous solution which was maintained at about 5° C. untilits addition to the aqueous phase during copolymerization. For themacroreticular resin, the same procedure was followed using 10.2 g BMAPmonomer, 11.62 g styrene; 8.18 g 55% DVB, 9.90 g VMP Naphtha and 0.16 gVazo 52.

The suspension copolymerization of each monomer phase was then carriedout according to the procedure of Example 1. Confirmation of eachcopolymer composition was by I.R. and elemental combustion analysis. Thegel resin appeared as translucent, generally spherical and smooth beadsthat were consistent with the overall physical properties of the othermaterial described in the specification in accordance with theinvention. The macroreticular resin similarly appeared as generallyspherical and smooth bead particles also of a substantially uniform sizeand appearance, but with a whitish color consistent with the presence ofsubstantial microporous channels throughout the bead structurecharacteristic of such materials. Porosity was confirmed by surface areameasurements (ca. 30 m² /g). Both polymer resins proved hard an durablewhen used in the following reactions and were then recovered forrecycling in each case after washing with appropriate solvents todisplace any residual water present.

Ester Rearrangement Study

For the purpose of testing and comparing the catalytic effectiveness ofthese 15% cross-linked gel and macroreticular resins, a dimedonerearrangement reaction was studied in which3-isobutyryloxy-5,5-dimethyl-2-cyclohexenone was converted to2-isobutyryl-5,5-dimethyl-1,3-cyclohexanedione. A stock solution of21.03 g (0.1 mol) 3-isobutyryloxy-5,5-dimethyl-2-cyclohexenone withtoluene was then prepared and filled to the line in a 100 ml volumetricflask. A 10 ml aliquot of the solution was pipetted into the test tubecontaining a 1:1 gram equivalent amount of either the gel ormacroreticular resin catalyst prepared in the first part of thisExample. The tube was placed in a constant-temperature bath at 100° C.,and the reaction mixture was magnetically stirred for 25 hours withsamples taken at various times. The gas chromatographic (GC) conditionswere set at 12 m DBI @ 160° C. After the last sample was taken, thereaction mixture was left to filter for 2 hours and weighed. From the GCassay, the percent conversion based on the amount of starting materialremaining was then calculated.

For the 15% cross-linked macroreticular resin catalyst, 75.7% conversionwas detected after 4 hours and 97.5% conversion after 24 hours in theheated water bath. For the 15% cross-linked gel material, 79.7%conversion occurred after 4 hours and 98.0% conversion after 24 hours ofreaction. Similar testing and calculations were then made usinghomogeneous DMAP material. A comparison was made by dividing the percentconversion for the polymer-supported BMAP material by the correspondingconversion using DMAP multiplied by 100 to convert to a percentage. Thispercent conversion comparison relative to DMAP for both themacroreticular and the gel resins was 79.0 and 83.2, respectively, after4 hours and was 98.3 and 99.3%, respectively, after 24 hours. In eachcase, this reflects a effective result demonstrating the significantcatalytic activity of the polymer-supported BMAP material prepared inaccordance with the invention relative to the known DMAP standard.

Acetylation of 1-Methylcyclohexanol Study

For the further purpose of testing and comparing the catalytic utilityof these 15% cross-linked materials, a procedure similar to the esterrearrangement was used for the acetylation of 1-methylcyclohexanol. Astock solution was first prepared with 30 ml triethylamine (TEA) and 20ml 1-methylcyclohexanol pipetted into a 200 ml volumetric flask whichwas filled to the line with toluene. The polymer-supported BMAP catalyst(0.41 mmol, 5 mol %) was added to the culture tube and 10 ml of thestock solution which contained 1 ml (8.1 mmol) 1-methylcyclohexanol and1.5 ml TEA (10.8 mmol) was also pipetted into the tube. After stirring10 minutes in a 60° C. constant-temperature bath, 1.5 ml aceticanhydride (15.8 mmol) was added to the tube. Stirring at 60° C. wascontinued and at various times, samples were taken for determiningconversions. After 24 hours, the tube was removed from the hotchloroform bath, and the catalyst was washed with toluene, filtered offand dried for 2 hours. Visual inspection of both the gel andmacroreticular resins showed that the beads had held up well during thereaction, with any deterioration evident being the result of thestirring method used in the experiment. It is understood thatalternative stirring techniques such as used in Example 1 will eliminatecatalyst breakage due to this cause.

Following GC analysis of the samples, it was determined that for the 15%cross-linked macroreticular resin, 21.6% conversion to the acetateoccurred after 6 hours while 37.1% was converted after 24 hours in thebath. For the 15% cross-linked gel resin, the corresponding values were25.4% conversion after 6 hours and 38.1% conversion after 24 hours.These conversions were then compared relative to similar DMAP-catalyzedreactions with the percent conversion relative to DMAP for themacroreticular resin being 27.1% after 6 hours and 38.4% after 24 hours,and for the gel resin being 31.9% and 39.4%, respectively. As with theester rearrangement, this testing confirmed the effective catalyticactivity of both the gel and macroreticular resins prepared according tothe applicants' invention. This was true even with the high 15% crosslinking in these resins which is substantially greater than may bedesired under the circumstances of a particular reaction. As thiscross-linking decreases, activity levels would increase both in absoluteterms and relative to similar DMAP conversions.

EXAMPLE 5 Comparison of Aqueous Phases

Suspension copolymerizations were carried out in the manner described asfollows comparing one of the preferred aqueous phases in the inventionusing Methocel 50-123 as the stabilizing additive against the aqueousphases reported by groups led by Tomoi (Tomoi, M., and Ford, W. T., J.Am. Chem. Soc., 103, 3828 (1981)), and Frechet (Deratini, A., Darling,G. D., Horak, D., and Frechet, J. M. J., Macromolecules, 20, 767 (1987))and comparing the preferred organic phase in the invention against thealternative recommended by Frechet (Deratini, A., Darling, G. D., Horak,D., and Frechet, J. M. J., Macromolecules, 20, 767 (1987)).

Preparation of Aqueous Phases

The Tomoi aqueous phase was prepared by mixing a solution containing1.35 g gelatin, 12.5 g Merquat 100 (which ispoly(diallyldimethylammonium chloride) marketed by Calgon Corp.,Pittsburg, Pa.) and 5.1 g boric acid in 450 g of water. Its pH wasadjusted to 10.0 with a 25% aqueous solution of sodium hydroxide.

The Frechet aqueous phase was prepared by simply dissolving 6.75 gpolyvinylalcohol (Airvol 523 manufactured by Air Products and Chemicals,Inc. of Allentown, Pa.) in 450 g of water.

The aqueous phase in accordance with the present invention which was inthis test was prepared as described in Example 4.

Preparation of Organic Phases

Two organic phases were prepared for use in the comparison. The firstinvolved subsequent attachment of 4-(N-methylamino)pyridine groups to apreformed cross-linked chloromethylated polystyrene. This procedure waspreferred by Frechet and the initial organic phase was prepared as asolution containing 23.75 g styrene, 8.35 g chloromethylstyrene, 2.4 g55% DVB and 0.1 g Vazo 52, which was maintained between about 0°-10° C.before copolymerization. The second procedure preferred by theapplicants involved direct copolymerization of a comonomer solution ofstyrene and the vinyl-substituted BMAP monomer. This required preparinga solution containing 11.2 g of the BMAP monomer, 18.94 g styrene, 2.37g 55% DVB and 0.16 g Vazo 52 according to Example 2 which was alsomaintained between about 0°-10° C. before copolymerization.

Copolymerization and Results

The copolymerization reactions in this Example were carried out usingthe same procedure and amounts as in Example 1. Following cooling andremoval of the insoluble product by filtration, the following resultswere observed:

The cross-linked copolymers prepared using the Tomoi aqueous phase andboth organic phases yielded particles that were not uniformly sphericaland varied greatly in size. The products contained a significant amountof flake and fine powders, making it very difficult to filter or recoverfrom any commercial process. The distorted beads showed visible signs offractures under microscopic analysis and readily broke into smallerfragments upon swelling and recapture from a toluene solvent. Similarly,severe fracturing was noted when a slurry of this material in toluenewas stirred for several hours.

The cross-linked copolymers prepared using the Frechet aqueous phase andboth organic phases consisted substantially of clumps of small distortedbead forms. Attempts to separate these particles resulted in substantialfracture of the discernable beads present in the material. Microscopicexamination of these bead clumps revealed both fractures and many tinybubbles and other imperfections in the particles. Similar to the Tomoimaterial, these copolymers also broke into smaller fragments uponrepeated swelling in toluene and upon stirring in a slurry for severalhours.

The cross-linked copolymers prepared using the aqueous phase of thepresent invention (with both organic phases) produced materials inyields over 90% by weight consisting primarily of smooth spherical beadsthat were hard and translucent giving all appearances of a superior gelresin structure. The beads were substantially uniform in size withminimal deviation of about 10% from the median or average bead size ineach case. Little or no extraneous irregular-shaped material wasproduced, and microscopic examination showed no signs of fractures orbubbles in the produced particles. Of equal importance, neither repeatedswelling in toluene nor nondestructive stirring in a toluene slurry formore than two days resulted in any significant fracturing of the beadsthereby confirming their durability for recycling in many acylation,alkylation and other related reactions of commercial significance.

EXAMPLE 6 Preparation of the Hydrobromide Salt of Vinyl-Substituted BMAPMonomer (N-vinylbenzyl-N-methyl-4-pyridylamine hydrobromide)

To a dry, nitrogen-purged round-bottom flask is charged4-(N-methylamino)pyridine (43.26 g), sodium hydride (80 wt. % in mineraloil, 14.9 g), and anhydrous tetrahydrofuran (250 mL). After 2.5 hr,vinylbenzyl chloride (a mixture of about 60 wt. % 3-vinylbenzyl chlorideand about 40 wt. % 4-vinyl benzyl chloride, according to themanufacturer) is added. The temperature is maintained below 40° C. for 4hr. Excess sodium hydride is destroyed by addition of water. Afterfiltration of insoluble salts, a solution of 30 wt. % hydrogen bromidein acetic acid (80.1 mL) is added with stirring while the temperature ismaintained below 30° C. After 15 minutes the hydrobromide salt of BMAPmonomer is isolated as a solid by filtration. The solid is furtherpurified by dissolving in 800 mL of dichloromethane, then precipitatedby the addition of 800 mL of tetrahydrofuran, to yield 52.6 g (43%) ofN-vinylbenzyl-N-methyl-4-pyridylamine hydrobromide as a crystallinesolid, m.p. 169°-171° C. The structure and composition were confirmed byNMR and elemental combustion analysis. This material was stable tostorage and could be converted by treatment with base to BMAP monomerwhich was suitable for copolymerization as described above.

EXAMPLE 7 Preparation of the Hydrochloride Salt of BMAP Monomer(N-vinylbenzyl-N-methyl-4-pyridylamine hydrochloride)

Using the method of Example 6 but substituting hydrogen chloride forhydrogen bromide gave 72% of N-vinylbenzyl-N-methyl-4-pyridylaminehydrochloride, m.p. 173°-175° C. The structure and composition wereconfirmed by NMR, combustion elemental analysis and silver nitratetitration.

EXAMPLE 8 Preparation of the p-toluenesulfonate Salt of BMAP Monomer(N-vinylbenzyl-N-methyl-4-pyridylamine p-toluenesulfonate)

Using the method of Example 6 but substituting p-toluenesulfonic acidhydrate for hydrogen bromide gave 50% ofN-vinylbenzyl-N-methyl-4-pyridylamine p-toluenesulfonate, m.p.129°-131.5° C. The proposed structure was confirmed by NMR and IR.

EXAMPLE 9 Preparation of the Methanesulfonate Salt of BMAP Monomer as anAqueous Solution, and Conversion of it to Free BMAP Monomer

To a dry, nitrogen-purged round-bottom flask was charged4-(N-methylamino)pyridine (4.33 g), sodium hydride (80 wt. % in mineraloil, 1.5 g), and 25 mL of anhydrous tetrahydrofuran. After 2.5 hr ofagitation, hydrogen evolution ceased and toluene (60 ml) was introduced.The tetrahydrofuran was removed by distillation. Vinylbenzyl chloride (amixture of 3-and 4-vinylbenzyl chloride, 6.36 g) was added, and thetemperature was kept below 40° C. for 4 hr. Excess sodium hydride wasquenched by addition of water. Sodium chloride was removed byfiltration. Aqueous 50 wt. % methanesulfonic acid (23 g) was added tothe toluene solution while keeping the temperature below 40° C. Twolayers were formed. The aqueous layer containedN-vinylbenzyl-N-methyl-4-pyridylamine methanesulfonate was separatedfrom the toluene layer. The remaining toluene layer contained mineraloil, some unreacted vinylbenzyl chloride, and other impurities, and wasdiscarded. Aqueous ammonia (28 wt. %) was then added to the acidsolution of BMAP monomer methanesulfonate until the pH reached 9.2. Theresulting suspension was extracted with dichloromethane, the extractdried over magnesium sulfate, and evaporated to yield the BMAP monomerfree base as a clear, viscous brown oil which solidified on standing.The NMR and IR spectra were identical with those of a purified sample ofBMAP monomer free base. The monomer was suitable for copolymerizationwith styrene and divinylbenzene, in the manner described in Examples 1through 5.

EXAMPLE 10 Preparation of the Sulfate Salt of BMAP Monomer as an AqueousSolution, and Conversion of it to Free BMAP Monomer

The process of Example 9 was repeated, except that sulfuric acid (20 mLof 6M) was substituted for the aqueous methanesulfonic acid. BMAPmonomer (7.91 g, 88% yield) was obtained, and was found to be 94.6% pureby gas chromatography.

EXAMPLE 11 Preparation of the Formate Salt of BMAP Monomer as an AqueousSolution, and Conversion of it to Free BMAP Monomer

The process of Example 9 was repeated, except that 90 wt. % formic acid(5.1 mL) was substituted for the aqueous methanesulfonic acid. BMAPmonomer was obtained in 86% yield and was 95.8% pure by gaschromatography.

EXAMPLE 12 Preparation of the Phosphate Salt of BMAP Monomer as anAqueous Solution, and Conversion of it to Free BMAP Monomer

The process of Example 9 was repeated, except that 85 wt. % phosphoricacid (8.2 mL) was substituted for the aqueous methanesulfonic acid. BMAPmonomer was obtained in 92.3% yield and was 96% pure by gaschromatography.

EXAMPLE 13 Preparation of Polymer-Supported 4-(N-benzyl-N-methylamino)pyridine Catalysts

To a dry, nitrogen-purged round-bottom flask was charged4-(N-methylamino)pyridine (43.26 g), sodium hydride (80 wt. % in oil,14.9 g), and anhydrous tetrahydrofuran (250 mL). After hydrogenevolution ceased, toluene (600 mL) was added and most of thetetrahydrofuran was removed by distillation. A mixture of 3- and4-vinylbenzyl chloride (commercial vinylbenzyl chloride, 63.6 g) wasadded. The temperature was maintained below 40° C. for 6 hr. Excesssodium hydride was quenched with water and carbon dioxide. Sodiumchloride was separated by filtration.

To the filtrate was added 18 wt. % hydrochloric acid (115 mL) whilemaintaining the temperature below 40° C. The aqueous layer, containingthe BMAP monomer hydrochloride, was separated and washed with toluene.Aqueous ammonia (28 wt. %) was added to the aqueous layer until the pHwas 9.0. Styrene (141.2 g) was added and the aqueous layer was separatedand discarded. The toluene solution was washed once with water. Theresulting toluene solution is found to contain 34.5 wt. % of BMAPmonomer by titration with perchloric acid in acetic acid. To a portion(217.9 g) of the styrene solution was added 17.1 g of 55 wt. %divinylbenzene and 1.17 g of Vazo 52(2,2'-azobis(2,4-dimethylvaleronitrile) while keeping the mixture atroom temperature.

An aqueous phase was prepared by dispersing 0.8 g of Methocel 50-123with stirring in 800 mL of water heated to 85° C., followed by coolingthe dispersion to 25° C. for 30 minutes. This aqueous suspension washeated to 58° C., stirred, and agitated. The styrene-BMAPmonomer-divinylbenzene-Vazo solution was then added below the liquidsurface to the stirred aqueous phase. The resulting dispersion wasmaintained at 58° C. for 3 hours, maintaining the nitrogen purge andagitation. The mixture was then heated at about 65° C. for 16 hours. Thedispersion was cooled and filtered to yield 219 g of highly sphericalbeads of polymer-supported 4-(N-benzyl-N-methylamino) pyridine found tohave useful catalytic activity.

EXAMPLE 14 Comparative Stability of BMAP Free Base and BMAPHydrochloride Salts Stability of the BMAP Free Base

26.1 g BMAP monomer was prepared by the Tomoi method as a toluenesolution. Toluene was removed at reduced pressure to give the BMAPmonomer free base as a dark viscous oil which was placed in a glassbottle and stored in a freezer at -5° C. for eight days. The resultingmonomer was stirred with excess cyclohexane and a residue, substantiallyrepresenting the spontaneous polymerization of the monomer, formed. Themonomer solution was decanted and the remaining residue washed with twomore portions of cyclohexane. After drying, the polymeric residue (3.2g) was found to represent 12% of the original monomer portion.

Stability of the BMAP Acid Salt Solution

25.3 g BMAP monomer in the free base form was prepared as describedabove to which 200 ml of aqueous hydrochloric acid (5%) was added. Theresulting solution was placed in a glass bottle and stored in arefrigerator at 3° C. for eight days. The solution was treated with aslight excess of sodium hydroxide and the resulting three phase mixtureextracted with cyclohexane to dissolve the BMAP monomer. The organic andaqueous layers were removed by decantation and the remaining polymericresidue washed with two additional portions of cyclohexane and dried.The residue, 1.3 g substantially comprising the spontaneouspolymerization product of the monomer, represented 5% of the originalmonomer portion.

Stability of the Solid BMAP Acid Salt

30.0 g of the solid BMAP hydrochloride salt prepared as in Example 7 wasstored in a glass bottle at room temperature for four weeks. Theresulting white solid appeared unchanged. The BMAP hydrochloride saltwas dissolved in 200 ml water and the resulting solution treated with150 ml aqueous sodium hydroxide (5%). Only a trace of residue (0.2 g)resulted, substantially comprising the spontaneous polymerizationproduct of the monomer, representing less than 1% of the originalmonomer portion.

What is claimed is:
 1. In preparing a vinyl-substituted4-(N-benzyl-N-methylamino)pyridine monomer for use in a polymerization,the improvement comprising the steps of isolating and purifying thecrude monomer once formed with an acid sufficiently strong to form asalt with said monomer for stable storage pending later use.
 2. Theprocess of claim 1 in which said isolating is by extraction of themonomer from a substantially water insoluble solvent.
 3. The process ofclaim 2 in which the acid is aqueous.
 4. The process of claim 3 in whichthe acid is selected from the group consisting of:hydrochloric acid;sulphuric acid; hydrobromic acid; p-toluenesulfonic acid;methanesulfonic acid; formic acid; and phosphoric acid.
 5. The processof claim 1 in which said isolating is by precipitation of the monomer.6. The process of claim 5 in which the precipitation is by exposing themonomer to the acid and further in which the acid is substantiallyanhydrous.
 7. The process of claim 6 in which the acid is selected fromthe group consisting of:hydrogen chloride; hydrogen bromide;p-toluenesulfonic acid; and methanesulfonic acid.
 8. The process ofclaim 1 further comprising neutralizing the isolated monomer with a baseprior to later use.
 9. The process of claim 8 in which the base isaqueous.
 10. The process of claim 8 in which the base is selected fromthe group consisting of:ammonia; and sodium hydroxide.
 11. The processof claim 9 and further comprising extracting the neutralized monomerwith a substantially water insoluble solvent.
 12. The process of claim 9in which the solvent is styrene.
 13. The process of claim 1 in which thepolymerization is a suspension copolymerization.
 14. As a monomercomposition for subsequent use in polymerization, an isolated acid saltform of the reaction product from preparation of vinyl-substituted4-(N-benzyl-N-methylamino)pyridine.